The invention relates to loudspeakers and, more particularly, to loudspeaker drivers. The invention particularly relates to drivers for the class of loudspeakers known as bending wave speakers, e.g. of the kind described in WO97/09842.
Merchandising displays, toys and novelties are known which contain some form of sound generator that produces speech, music or other audible output associated with the display or article. See, e.g., Smith U.S. Pat. No. 2,524,143; Wilson U.S. Pat. No. 4,299,041; Wilbur U.S. Pat. No. 4,363,081; Dxc3x6ring U.S. Pat. No. 4,425,098; Galloway U.S. Pat. No. 4,611,262; Azima U.S. Pat. No. 6,181,799; Azima U.S. Pat. No. 6,285,770; and Yu GB 2 268 119.
It is an object of the invention to enhance the utility of sound-emitting display signs such as point of purchase or sale advertising display boards. It is a further object of the invention to provide an inexpensive and even disposable drive unit, which may be self-contained, for loudspeakers in objects such as toys, novelties and merchandising, such as point of sale or point of purchase advertising display boards.
According to the invention there is provided a drive module for attachment to a rigid panel and adapted to apply bending wave energy at audio frequencies to the panel whereby the panel can radiate an audio output. The drive module comprises a housing adapted to be secured to the panel, at least one foot on the housing and adapted to fix the housing securely to the panel, an electro-mechanical transducer in the housing, a support for the transducer in the housing, the transducer being adapted to contact the panel to apply bending wave energy thereto when energised with an electrical audio signal, and an audio signal amplifier in the housing.
When attached to a rigid panel the drive module thus forms a loudspeaker.
The foot may be providing with one or more pressure sensitive adhesive pads to fix the housing to the panel. The foot structure may be continuous or may comprise a plurality of spaced feet.
The transducer may be piezoelectric or of the magnet and coil variety. The transducer may be inertial, in which case it is compliantly mounted on the housing, or may be grounded on the housing. The transducer may be adhesively fixed to the panel. Thus where the transducer is an electrodynamic device, it may be compliantly mounted, via its magnet to the housing, and may be adhesively fixed, e.g. via a pressure sensitive panel and via its voice coil to the panel.
Preferably the mounting of the housing on the panel is compliant. Thus the portion(s) of the housing in the region of the pressure sensitive adhesive may be resilient. This can be achieved by forming the housing with peripheral inwardly directed resilient flanges to form the foot or feet.
The audio signal amplifier may be resiliently mounted in the housing.
The housing may be perforated to allow audio energy from the panel to pass through the housing.
The housing may carry one or more electric dry cell batteries to power the signal amplifier. These batteries may be substantially symmetrically disposed around the transducer to help equalise force distribution on the transducer suspension.